The Bush administration is expelling four Cuban diplomats from the United States over the case of a former U.S. military intelligence analyst who was convicted last month of spying for Cuba. U.S. officials describe that spy case as "extremely serious."

The expulsion decision applies to two senior officials at Cuba's "interest section" at the Swiss embassy in Washington, and to two diplomats from Cuba's mission to the United Nations in New York.

The State Department said it informed Cuban authorities of the decision last Friday, and that all four diplomats were given 10 days to leave the United States.

Confirmation of media reports of the expulsions came from State Department spokesman Richard Boucher.

He made clear the move was retaliation for the case of Ana Belen Montes, the former senior analyst for Cuban affairs at the U.S. Defense Intelligence Agency, who was sentenced last month to 25 years in prison for spying for the Castro government.

"These expulsions represent our response to the unacceptable Cuban activities for which Ana Belen Montes was arrested and convicted. As you all remember, she was a defense intelligence analyst who conducted espionage for Cuban against the United States. We call upon the Cuban government to assure that there will be no similar episodes or new actions in the future against the interests of the United States," Mr. Boucher said.

He called the Belen Montes case "extremely serious" and only the latest in a long record of Cuban espionage against the United States.

News reports said Belen Montes passed information to Cuban intelligence officers over several years, including the names of at least four covert U.S. agents working in Cuba.

She admitted guilt as part of a plea arrangement under which she received a reduced sentence and agreed to cooperate with investigators.

Spokesman Boucher did not accuse the two Cuban officials in Washington, first secretaries Oscar Redondo Toledo and Gustavo Machin Gomez, of a role in the Belen Montes case or other espionage.

But he said the two staffers of the Cuban mission in New York were being asked to leave for engaging in activities "harmful to the United States" and "outside their official capacity" at the U.N. - diplomatic language that suggests spy activity.

Cuba and the United States do not have diplomatic relations but maintain the interest sections in each other's capital under auspices of the Swiss embassies.